1. Field of the Invention
The present invention relates to a method for managing a plurality of frame buffers storing moving image data, and more particularly to a method for managing a plurality of frame buffers storing replayed image data obtained by a decoding process in the decoding system of moving image data compressed and encoded according to a variety of standards, such as MPEG and the like.
2. Description of the Related Art
As a standard specification concerning moving image compression and encoding, a variety of standards such as H.261 corresponding to ISDN moving image transfer, H.262 corresponding to broadcast media moving images, H.263 corresponding to the existing telephone network television telephone, MPGE-1 corresponding to storage media moving images, MPEG-2 as the same standard as H.262, MPEG-4 corresponding to multimedia, such as computer, communication, broadcasting, home appliance, etc. are used. In a system for decoding stream data encoded based on such a standard, a lot of frame buffers for storing replayed image data obtained by a decoding process, and after storing the image data of each frame in a frame buffer, the image data is displayed, for example, on a display screen.
However, since the volume of moving image data is usually enormous and the number of frame buffers for storing it is limited, the vacancy of a frame buffer must be appropriately managed and image data must be stored. Conventionally, for example, a flag for indicating whether a frame buffer stores data is provided, frame buffers are all retrieved and data is stored in a vacant frame buffer. However, there are a lot of frame buffers and when a vacant frame buffer is found near the end of the retrieval, the retrieval takes a lot of time.
As the prior art of a storage area management method for memory, such as a frame buffer or the like, Patent reference 1 discloses a technology capable of solving a problem that, in the management of the working area of frame memory or the like, an area cannot be assigned, depending on a required shape even when there is space sufficient to satisfy a requirement on memory and the efficiency in use of the working area degrades.
Patent reference 2 discloses a technology in which in a method for managing a memory area in units of rectangles, a memory management table corresponding to an adjacent area is provided with a left connection pointer and an upper connection point and an area of an arbitrary size can be used.
Patent reference 1: Japanese Patent Application Publication No. H3-44747 “Memory Management Processing Method”
Patent reference 2: Japanese Patent Application Publication No. H3-154973 “Memory Management Method”
However, when a frame buffer storing valid data and a vacant frame buffer are arrayed at random, such prior arts cannot improve the retrieval speed of a frame buffer in which data is subsequently stored or whose data is replayed.